//
//  Copyright 2012, Xamarin Inc.
//
//    Licensed under the Apache License, Version 2.0 (the "License");
//    you may not use this file except in compliance with the License.
//    You may obtain a copy of the License at
//
//        http://www.apache.org/licenses/LICENSE-2.0
//
//    Unless required by applicable law or agreed to in writing, software
//    distributed under the License is distributed on an "AS IS" BASIS,
//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//    See the License for the specific language governing permissions and
//    limitations under the License.
//
using EmployeeDirectory.Core.Data;

namespace EmployeeDirectory.Core.ViewModels;

public class PeopleGroup : IEnumerable<Person>
{
	public string Title { get; private set; }

	public List<Person> People { get; private set; }

	public PeopleGroup (string title)
	{
		Title = title;
		People = new List<Person> ();
	}

	public static ObservableCollection<PeopleGroup> CreateGroups (IEnumerable<Person> people, bool groupByLastName)
	{
		var pgs = new Dictionary<string, PeopleGroup> ();

		foreach (var p in people.OrderBy (x => x.LastName)) {
			
			var g = groupByLastName ?
					p.SafeLastName.Substring (0, 1).ToUpperInvariant () :
					p.SafeDisplayName.Substring (0, 1).ToUpperInvariant ();
			
			PeopleGroup pg;
			if (!pgs.TryGetValue (g, out pg)) {
				pg = new PeopleGroup (g);
				pgs.Add (g, pg);
			}
			
			pg.People.Add (p);
		}

		return new ObservableCollection<PeopleGroup> (pgs.Values.OrderBy (x => x.Title));
	}

	IEnumerator<Person> IEnumerable<Person>.GetEnumerator ()
	{
		return People.GetEnumerator ();
	}

	System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator ()
	{
		return People.GetEnumerator ();
	}
}
